JPH07314545A - Production of hollow container - Google Patents

Abstract

PURPOSE:To prevent distortion at the time of thermal sterilization by radially bulging leg parts on the bottom of a biaxially stretched blow molded container around the central part thereof so that the container can stand alone, disposing a shield having openings corresponding to the central part of the bottom and the peripheral part of the leg between the bottom part and a heater, and heating the corresponding parts to cause crystallization. CONSTITUTION:A biaxially stretched blow molded container 1A is provided, on the bottom and the peripheral part thereof, with leg parts 32 so that the container can stand alone. A shield 2A having openings corresponding to the central part of the bottom and the peripheral part of the leg 32 is disposed between the bottom part and a heater 3. When the container is thermally sterilized by means of the heater 3, heat is transmitted through the openings to the central part and the leg parts 32 to cause crystallization. Consequently, the container 1A is sterilized thermally, while standing alone, without causing distortion at the central part and the leg parts 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pressure- and heat-resistant self-supporting hollow container, and more particularly to a hollow container which has improved pressure resistance and heat resistance during heat sterilization of contents and is also excellent in impact resistance. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Conventionally, as a pressure- and heat-resistant self-standing hollow container, a bottom cup is bulged to form a hemispherical shell in order to enhance the inner pressure resistance of the container body, and a base cup molded into a bottomed cylindrical shape is added to this. The most popular type of container is that it is attached to the container to make it self-supporting. However, the use of the base cup requires that the base cup be separately molded and mounted and fixed.
The weight of the container becomes large and the shape also becomes large, and the heat sterilization of the contents cannot be performed smoothly because the hot water does not reach the bottom of the container sufficiently in the heat sterilization process. -There were various problems such as water being accumulated in the scoop, and it was difficult to drain it quickly.

Further, it is desired to effectively reuse a used empty container from the viewpoint of resource saving and environmental problems.
In a container equipped with a base cup, the container body and base are usually used.
Since the materials of the scup and the adhesive are different, they must be separated when they are reused, and there is a problem that the process cost becomes high.

Due to these problems, a pressure and heat resistant container which does not require a base cup has been desired. Several proposals have been made for pressure-resistant containers that do not require a base cup, and generally, a plurality of legs are radially bulged around the center of the bottom, and valleys are formed between these legs. It is either a structure in which a line portion is formed or a champagne type structure. For example, it is described in JP-B-48-5708, JP-B-59-40693, JP-B-61-9170, JP-A-63-202424 and JP-A-3-43342.

However, although the container described in each of these items can obtain satisfactory performance as a pressure resistant container, it obtains sufficient performance when used as a pressure resistant heat resistant container for performing a heat sterilization process. I can't. That is, in the containers described in the above items, since the unstretched region and the low stretched region exist in the center of the bottom and the periphery of the center, the temperature of the contents during heat sterilization is from 50 ° C to 70 ° C.
When the temperature rises to about 0 ° C, the internal pressure increases and the container material itself easily undergoes creep deformation.
The unstretched region and the low-stretched region around the center of the bottom and the periphery of the center undergo creep deformation to project, and the container loses self-standing stability.

As a method for solving this problem, for example,
It is conceivable to use the container described in JP-A-5-85535. Since this container is a container in which the center of the bottom is crystallized and the periphery of the center is sufficiently stretched, creep deformation of the bottom can be suppressed to some extent when the internal pressure increases during heat sterilization. However, even in the case of this container, it is difficult to sufficiently stretch the valley line portion formed between the leg portions and a low stretched region remains in the portion, so that the portion creeps during heat sterilization. Deformation causes the bottom to protrude and loses independence stability.

[0007]

As a result of earnest research, the researchers of the present invention have found that a plurality of legs are radially bulged around the center of the bottom, and a valley line is formed between these legs. In the case of the bottom structure that forms the part, it is found that the stress due to the internal pressure concentrates especially on the center part of the bottom and the valley line part, and in the bottom protrusion during actual heat sterilization, the part of the valley line part near the center part It was discovered that the creep deformation of was extremely large.

The present invention has solved the above-mentioned problems, and it has been proposed that the space between the bottom of the biaxially stretched blow container and the heating device be
(A) Bottom central part and / or (B) Bottom central part peripheral part and / or (C) Valley part close to bottom central part and / or (D) Leg part of said peripheral part A portion from the edge to the ground portion and / or (E) a portion corresponding to the portion between (C) and (D) is opened, and a shielding plate having a shape fitting with the bottom of the container is installed, By heating and crystallizing the part selected from (A) to (E) of the bottom, the bottom does not undergo creep deformation during heat sterilization of the container to lose self-sustaining stability, and chemical resistance And a method for producing a pressure- and heat-resistant self-standing hollow container, which is excellent in

[0009]

The first invention of the present invention is as follows:
It has a self-supporting structure in which a plurality of legs are radially bulged around the mouth, neck, shoulder, torso, and center of the bottom, and valley lines are formed between these legs. A biaxially stretched blow container made of a saturated polyester, which is made of a bottom and is made of saturated polyester. Between the bottom of the container and the heating device, (A) the center of the bottom and / or (B) the center of the bottom. The peripheral portion and / or (C) the central portion side of the valley line portion and / or (D) the portion from the edge of the peripheral portion to the ground portion and / or (E) the (C) and ( A portion corresponding to the portion between D) is opened, a shielding plate having a shape fitting with the bottom of the container is installed, and a portion of the bottom of the container selected from (A) to (E) is heated to crystallize. A second aspect of the present invention is a method for producing a pressure- and heat-resistant self-supporting hollow container, comprising: Akira biaxial stretch blow molding, saturated polyester of the biaxially stretched blow molded container is a method for producing a pressure-resistant heat-resistant self-supporting hollow container has at least one of the following (a) ~ (d). (A) Crystallized mouth and neck. (B) Crystallized support ring. (C) Crystallized under support ring. (D) The mouth / neck portion or the mouth / neck portion and the support ring have an inner diameter of 60 to 80% of the outer diameter, and stress and strain are relaxed by heating.

The present invention will be described in detail below. In the present invention, a device that generates heat can be used as the heating device, and specifically, an infrared heater, hot air, an infrared lamp, a quartz tube heater, a high frequency heating device, or the like can be used. Further, it goes without saying that a heat source other than this can be used.

Further, in the present invention, the material of the shielding plate is a metal such as aluminum, iron or copper or a heat resistant resin,
Ceramic or the like can be used, and the surface of the shielding plate is preferably smooth.

The resin used in the hollow container of the present invention is preferably a thermoplastic polyester resin whose main repeating unit is ethylene terephthalate, and the thermoplastic polyester resin contains a homopolymer of polyethylene terephthalate as a main component.

As this thermoplastic polyester resin,
Some of the terephthalic acid components are aromatic dicarboxylic acids such as isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid; hexahydroterephthalic acid, hexahydroisophthalic acid Alicyclic dicarboxylic acids such as; adipic acid, sebacic acid, azelaic acid and other aliphatic dicarboxylic acids; P-
A copolymer obtained by substituting at least one other difunctional carboxylic acid such as oxyacid such as β-hydroxyethoxybenzoic acid and ε-oxycaproic acid can be used.

In the thermoplastic polyester resin, a part of the ethylene glycol component is used, for example, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentylene glycol, diethylene glycol, 1,1-cyclohexanedimethylol. , 1,4-cyclohexanedimethylol, 2,2 (4'-β-hydroxyethoxyphenyl)
It may be a copolymer obtained by substituting one or more polyfunctional compounds of other glycols such as sulfonic acid and functional derivatives thereof for copolymerization.

The intrinsic viscosity of the thermoplastic polyester resin used in the container of the present invention is preferably 0.7 to 0.9, and particularly preferably 0.75 to 0.80.

Further, for the thermoplastic polyester resin used in the present invention, additives such as a colorant, a heat deterioration preventing agent, an antioxidant, an ultraviolet absorber, an antistatic agent, an antibacterial agent and a lubricant may be appropriately used. it can.

The shielding plate of the present invention is provided with (A) the center of the bottom of the bottom of the biaxially stretched blow container and / or (B) the periphery of the center of the bottom and / or (C) the center of the bottom of the valley. Part and / or (D) a part from the edge of the peripheral part of the leg part to the ground part and / or (E) a part selected from the part between (C) and (D) The corresponding portion has an opening and has a shape that fits with the bottom of the container. Among the combinations of (A) to (E) above,
Particularly preferred is a combination comprising (B) and (C),
(E) can be combined as needed. The shielding plate has a shape that fits with the bottom of the container,
The engraving for fitting is such that 60% or more, preferably 80% or more, of the bulging portion of the leg portion is inserted. As a result, heat shrinkage due to heating can be prevented, and only the portion corresponding to the opening of the shielding plate can be heated and crystallized with high accuracy.

As a specific example of the manufacturing apparatus of the present invention, there is an apparatus shown in FIG. In FIG. 1, the basic configuration is
The bottom plate 7, the heating device 3 is installed on the bottom plate 7, and the shielding plate 2A is installed above the bottom plate 7. This shielding plate has the same engraving as the shape of the bottom of the biaxially stretched blow container 1A, the center of the bottom (A) of the bottom of the biaxially stretched blow container, (B) the peripheral part of the center of the bottom, and (C) the valley line. Corresponding to the part selected from the part near the center of the bottom of the part, (D) the part extending from the peripheral edge of the leg part to the ground part, and (E) the part between (C) and (D). It is a shield plate made of aluminum having an opening. The shield plate has a cooling water tube connected to a cooling water pipe provided for cooling, and a cooling water pipe provided in the shield plate for cooling the shielding plate. Further, a shield plate support plate 6 for supporting the shield plate 2A, a container support plate 5 for supporting the biaxially stretched blow container 1A installed above the support plate 22A, an upper plate 4 installed above it, and an upper plate 4 are installed. It was erected upright with the supported container lifting / loading cylinder 8, the container pressure loading cap pressing plate / container supporting plate 10 connecting the container lifting / loading cylinder 8 and the container supporting plate 5, and the bottom plate 7. , A shielding plate supporting plate 6, a container supporting plate 5 and a support 9 for supporting the upper plate 4.

A heating device 3 installed below the shield plate 2A.
The heat generated by the heat is transmitted from the opening of the shielding plate to the bottom of the biaxially stretched blow container, and by heating the specified portion of the bottom for a certain period of time, the specified portion of the bottom of the container can be crystallized. At this time, since the shielding plate is cooled by the cooling water, heat is not transmitted to the bottom portion of the container other than the above-mentioned opening portion, so that it is not crystallized. At this time, the temperature of the surface of the shielding plate that is in contact with the biaxially stretched blow container is preferably a temperature not higher than the Tg of the thermoplastic polyester resin. In the present invention, it is convenient and preferable to install the cooling water pipe on the side of the bottom of the container, but it is also possible to install it on other parts.

The shield plate 2A has a shape that fits with the bottom of the container. It is preferable that the shield plate and the container bottom are in contact with each other at the time of fitting, but there may be a gap as long as a portion other than a desired portion is not crystallized. Further, in order to improve the degree of adhesion, a method of manufacturing by pressing can be used. When the container is installed on the container support plate at a position substantially corresponding to the engraving on the shield plate, when the bottom part is inserted into the shield plate, the container rotates so that the bottom part matches the shape of the shield plate, The bottom of the container and the shield can be fitted well.

When crystallizing the bottom of the container, internal pressure may or may not be applied to the biaxially stretched blow container.
In the case of manufacturing by applying internal pressure, as shown in FIG. 2, the apparatus includes a container internal pressure load cap 11 to be mounted on the mouth / neck portion 21 of the container and a compressed air supply for supplying compressed air for applying internal pressure to the container. Packing 1 for preventing the compressed air sent into the tube 12 and the container from leaking from the mouth / neck portion 21.
It consists of three. Compressed air having an arbitrary pressure can be fed into the container from the compressed air feeding tube 12 to apply an internal pressure.

In the second invention of the present invention, the biaxially stretched blow container has at least one of (a) to (d), of which (a) + (b) + ( c),
(B) + (c) + (d), (c) + (d) and (a) +
The combination of (c) is preferable, and particularly preferably,
It is a combination of (a) + (b) + (c) and (b) + (c) + (d).

In the present invention, by crystallizing a specific part of the bottom of the hollow container, the chemical resistance to the lubricant used in the conveyor line of the filling factory can be improved and the occurrence of stress cracks can be suppressed. be able to.

[0024]

The present invention will be described in detail below with reference to examples. Example 1 Polyethylene terephthalate (manufactured by Nippon Unipet Co., Ltd., trade name RT553C) was injection molded to obtain a resin amount of 50.
0 g of a bottomed tubular preform was obtained. The (a) mouth and neck, (b) support ring and (c) under the support ring of this preform were heated by an infrared heater to be crystallized. After reheating this bottomed tubular preform, it is placed in a blow mold and stretched axially by a stretch rod while stretched in the circumferential direction by air blow, and then biaxially stretch blow-molded. Part 21 and support ring 22A
To obtain a biaxially stretched blow container having a draw ratio of 2.5 times in the axial direction and a draw ratio of 3.5 times in the radial direction in terms of the outer diameter ratio with the preform. At this time, while the body of the mold was heated to 120 ° C., heat setting was performed for about 10 seconds, and then air at room temperature was circulated in the blow container to cool it to obtain a biaxially stretched blow container. Next, between the bottom of the biaxially stretched blow container and the infrared heater (heating device), (A) the center of the bottom, (B) the periphery of the center of the bottom, (C) the center of the valley portion , And (D) a shield plate made of aluminum cooled by cooling water, which has a shape in which a portion corresponding to a portion from the edge of the peripheral portion to the grounding portion of the leg portion is opened and is fitted with the bottom portion of the container ( (Shown in FIGS. 4 and 5) is installed, the bottom of the container is fitted and adhered to the shielding plate, and the portions (A) to (D) are crystallized by heating, and the hollow container 1B shown in FIG. 3 (volume: 1.5 liters, total height 309 mm, body diameter 92 mm) were obtained. As shown in FIG. 6, the bottom of the hollow container 1B is a self-supporting structure in which five legs swell radially around the center at equal intervals and valley lines are formed between the legs. The bottom center part, the peripheral part of the bottom center part, the part near the bottom center part of the valley line part, and the part from the edge of the peripheral part of the leg part to the ground part are crystallized. , The density of the crystallized part is
It was 1.363 g / cm ³ .

In this hollow container 1B, at 5 ° C., 2.
After filling with 5 gas volumes of carbonated water and capping, the carbonated water returned to room temperature, and then a hot water shower at 70 ° C. was applied for 30 minutes. Then, it was showered with water at 20 ° C. for 10 minutes to cool, and the total height of the bottle and the deformation rate of the body diameter were measured. As a result, the total height of the hollow container is 307 mm.
The deformation rate of the body diameter was 0.9%. Next, when 12 filled containers were placed upright on the concrete from a height of 2.0 m, the bottom of the container was not broken in all cases.

Example 2 In Example 1, (c) as a preform, the lower part of the support ring was heated by an infrared heater to be crystallized,
(D) The inner and outer diameters of the mouth and neck and the support ring are 60 to 80% of the outer diameter, and the stress caused by heating is
The strain is relaxed, and the shielding plate shown in FIG. 7 and FIG. 8 is used, and (B) the peripheral part of the central part of the bottom of the biaxially stretched blow container container, (C) the central part of the bottom of the valley line part. Was performed in the same manner as above except that the portion close to the point (D) and the portion from the edge of the peripheral portion of the leg portion to the ground contact portion were crystallized. As shown in FIG. 9, the bottom of the obtained container is a self-supporting type in which five legs swell radially around the center at equal intervals and valley lines are formed between the legs. It has a structure, the peripheral part of the bottom center part, the part near the bottom center part of the valley line part and the part from the edge of the peripheral part of the leg part to the ground part are crystallized, and the crystallized part The density was 1.363 g / cm ³ .
The hollow container had a volume of 1.5 liters, a total height of 309 mm, and a body diameter of 92 mm.

This hollow container was filled with 2.5 gas volume of carbonated water at 5 ° C., capped, and after the carbonated water returned to room temperature, a hot water shower at 70 ° C. was applied for 30 minutes. Then, it was showered with water at 20 ° C. for 10 minutes to cool, and the total height of the bottle and the deformation rate of the body diameter were measured. As a result, the total height of the hollow container was 307 mm, and the deformation rate of the body diameter was 0.9%. Next, when 12 filled containers were placed upright on the concrete from a height of 2.0 m, the bottom of the container was not broken in all cases.

Comparative Example 1 In Example 1, (a) the mouth and neck of the preform,
The same procedure was performed, except that (b) the support ring and (c) the bottom of the support ring were not crystallized, and the bottom of the container was not crystallized. The hollow container had a volume of 1.5 liters, a total height of 310 mm, and a body diameter of 92 mm. This hollow container was filled with 2.5 gas volume of carbonated water at 5 ° C., capped, and after the carbonated water returned to room temperature, a hot water shower at 70 ° C. was applied for 30 minutes. Then, it was cooled by showering with water at 20 ° C. for 10 minutes. The bottom of the container of the bottle was protruding, and there was no self-sustaining stability.

[0029]

As described above, according to the present invention, by using a shielding plate having a specific shape to crystallize a specific portion of the bottom of the container, the pressure resistance and heat resistance during heat sterilization of the contents are increased. A pressure- and heat-resistant self-supporting hollow container with improved impact resistance can be obtained.

[Brief description of drawings]

FIG. 1 is a front view of the device of the present invention.

FIG. 2 is an enlarged view of the main part (F part) of FIG.

FIG. 3 is a sectional view of a hollow container 1B of the present invention.

FIG. 4 is a plan view of a shield plate 2A of the present invention.

FIG. 5 is a sectional view taken along the line A-A ′ of the shielding plate 2A of the present invention.

FIG. 6 is a bottom view of the hollow container of the present invention.

FIG. 7 is a plan view of a shield plate 2B of the present invention.

FIG. 8 is a B-B ′ sectional view of the shielding plate 2B of the present invention.

FIG. 9 is a bottom view of the hollow container of the present invention.

[Explanation of symbols]

1A Biaxially stretched blow container 1B Hollow container 2A, 2B Shielding plate 3 Heating device 4 Upper plate 5 Container supporting plate 6 Shielding plate supporting plate 7 Bottom plate 8 Container elevating / loading cylinder 9 Strut 10 Container internal pressure load Cap pushing plate and container supporting Plate 11 Internal pressure load cap 12 Compressed air inlet tube 13 Packing 14 Cooling water tube 15 Cooling water pipe 16 Opening 21 Mouth neck 22A Support ring 22B Support ring lower 23 Shoulder 24 Body 25 Bottom 31A Bottom center 31B Bottom Peripheral part of the central part 31C Bottom part of the valley line part Close to the central part 31D Bottom part of the leg Part from the peripheral edge of the central part to the grounding part 31a Opening corresponding to the central part of the bottom part 31b Peripheral part of the central part of the bottom part Corresponding opening 31c A portion near the center of the bottom of the valley line Corresponding opening 31d Around the center of the bottom of the leg From the edge of the part to the ground contact part Corresponding opening 32 Leg 33 Valley line

Claims (2)

[Claims] 1. A self-standing structure in which a plurality of legs are radially bulged around the mouth and neck, shoulders, torso, and center of the bottom, and valley lines are formed between these legs. In a biaxially stretch-blown container made of a saturated polyester biaxially stretch blow-molded having a bottom having a possible structure, between the container bottom and the heating device, (A) the center of the bottom and / or
(B) Peripheral part of the center of the bottom and / or (C) A part near the center of the bottom of the valley line part and / or (D) A part from the edge of the peripheral part to the ground part and / or , (E) A portion corresponding to the portion between (C) and (D) is opened, and a shielding plate having a shape that fits with the bottom of the container is installed. From (A) to (E) of the bottom of the container, A method for producing a pressure- and heat-resistant self-supporting hollow container, which comprises heating and crystallizing a selected portion. 2. The biaxially stretched blow container according to claim 1,
A method for producing a pressure- and heat-resistant self-standing hollow container having at least one of the following (a) to (d). (A) Crystallized mouth and neck. (B) Crystallized support ring. (C) Crystallized under support ring. (D) The mouth / neck portion or the mouth / neck portion and the support ring have an inner diameter of 60 to 80% of the outer diameter, and stress and strain are relaxed by heating.